The present invention is directed to a clamping chuck for holding drilling and/or cutting tools which have a cylindrical shank and the chuck includes at least two radially adjustable guide jaws and at least one radially adjustable engaging element which is engageable within the surface of the tool shank.
In the above type of clamping chuck it is known to transmit rotary motion to the cylindrical shank tool by friction-locking engagement of radially adjustable clamping jaws with the tool shank. The main advantage of such a chuck is that easily produced tools with smooth shank surfaces can be used. There is a substantial disadvantage, however, in that the rotary motion or torque transmitted by friction-locking engagement is limited. Chucks of this general type are usually not suited for percussion drilling, that is, for the simultaneous transmission of rotary motion and percussion motion which acts in the axial direction of the tool. Where such combined motion is to be transmitted, radially adjustable engaging elements are employed which fit into a recess in the cylindrical surface of the tool shank. This type of chuck is designed to handle only a single shank diameter and it cannot be adapted to a range of tool shank diameters.
In yet another clamping chuck three radially adjustable clamping jaws are provided as well as a radially adjustable engaging element incorporated into one of the clamping jaws. The clamping jaws are held within a conically shaped sleeve by means of a threaded ring and they can be pressed radially inwardly against the shank to be clamped. The engaging element projects radially inwardly from one of the clamping jaws and engages in a corresponding recess in the shank of the tool to be clamped. As a result, the engaging element can only be adjusted together with the clamping jaws. Therefore, only tools with a predetermined recess in the shank can be clamped in this particular chuck.